A simple way to circumvent the problem of measuring all required acoustric transfer functions for a user is to use a generic filter that is precomputed using, e.g., measurements on a dummy head. However, a precomputed equalization filter does not match the individual ear acoustics and can thus lead to a degraded perceived sound quality [1]}. Accurate estimates of the transfer function to the individual eardrum could be obtained using probe-tube measurements [2]}. However, probe-tube measurements are time-consming, delicate and thus difficult to obtain, which makes them unsuitable for many practical applications. Assuming that the pressure inside the ear canal does not vary substantially allows to use an in-ear microphone in a hearing device, e.g., a microphone placed at the inner face of an earmould. It is well-known that the sound pressure in the ear canal can vary substantially between the position of the eardrum and different positions along the ear canal [3]}, [4]}, and hence also the position the an in-ear microphone of a hearing device. Therefore, electro-acoustic models have been proposed to estimate the sound pressure at the individual eardrum based on an in-ear microphone [5]}, [6]}, [7]}. In this paper we consider a custom in-the-ear multi-microphone earpeice, as presented in [8]}, and use an estimate of the transfer between the receiver of the hearing device and the individual eardrum obtained from an electro-acoustic model of the hearing device and the individual ear canal [7]}. Furthermore, we propose to precompute the required transfer functions between the source and the occluded ear as well as the source and the open ear based on multiple measurements obtained from different subjects, similarly as done in [10]} for the open ear. This effectively allows to individualize the equalization filter with minimal measurement effort.
